Heat stabilization of petroleum mahogany sulfonates



test will for instance 'scribed Patented Nov. 1, 1949 HEAT STABILIZATION OF PETROLEUM MAHOGANY SULFONATES i Manuel Blumer, Petrolia j Pa., assignor to L.' Sonneborn Sons, Inc., a corporation of Delaware No Drawing. Application December 11, 1946, Serial No. 715,593

13 Claims. (Cl. 260-504) This invention'relates to new and useful improvements in the heat stabilization of petroleum mahogany sulfonates.

In the refining treatment of raw petroleum mahogany 'sulfon-ates as they are, for instance, obtained in the fuming sulfuric acid refining of petroleum oil distillates, these sulionates may be subjected to various purification steps, including color improving procedures. Many of these procedures, however, though capable of improving color to a desired extent, will yield products which are subject to subsequent objectionable darkening as for example in storage and especially at elevated temperatures. This darkening is due to the formation of relatively dark colored polymers of heat polymerizable substances resulting from the partial decomposition of the sulfonates. A petroleum mahogany sulfonate product of improved heat stability is described in the Liberthson and Blumer Patent No. 2,307,743 by the use of chlorite under specified controlled conditions. The heat stability test to which the products of this treatment respond is one of heating at 240 F. for 24 hours in asealed container without an observable deterioration in color value.

Under present day requirements and conditions of use, however, to which petroleum mahogany sulfonates are put, such test of heat stability, 1. e., heating for 24 hours at 240 F., has proven for many purposes unsatisfactory and insufliciently rigid. It was found that products answering this still be subject to appreciable darkening when stored in relatively large volume in metal and particularly iron containers or vessels at relatively high temperatures as may, for instance, maintain under conditions where stocks are required to be kept heated for relatively long periods of time to insure relative ease of flow and pumpa'bility of material. For this reason a more rigid test had to be devised. This test involves heating in sealed vessels or containers, preferably of iron, of the sulfonate product at a temperature of about 245-255" F. for in excess of 120 hours and preferably in excess of 168 hours. None of the col-or improved petroleum mahogany sulfonate products of the prior art, irrespective of their color values and including those obtained in accordance with the chlorite treatment prein the Liberthson-Blumer patent (2,307,743), can meet this test. They are all heat sensitive and will appreciably darken under these conditions. The more rigid test indicates the presence of heat polymerizable substances converted by the heat during the period of test to rel atively dark colored polymers. At least to some extent the polymerizable substances are the direct result of the color improving treatment, such as a chlorite or hypochlorite treatment causing partial decomposition of some of the sulfonates.

One object of the invention comprises inter alia a petroleum mahogany sulfonate product substantially free from heat polymerizab le substances tending to form upon heating dark colored polymers.

Another object of the invention comprises a petroleum mahogany sulfonate product substantially heat stable under the rigid conditions of test herein mentioned.

A further object of theinvention comprises such a petroleum mahogany-sulfonate product having an improved color value and preferably not exceeding 8R.

A still =f-urther object of the invention comprises a process for obtaining a substantially heat stable, and preferably also color improved, petroleum mahogany sulfonate product responding to the I rigid conditions of heat stability test herein mentioned. I

These and still further objects of the invention will be seen from the following description.

In accordance with the invention a suitable petroleum mahogany sulfonate solution in an organic solvent for said sulfonate is reacted in the presence of water with at least one member'selected from the group consisting of substantially water soluble inorganic and organic derivatives of hyposulf-urous and sulfoxylic acid in amount and for a period of time suflicient to obtain a color value for said sulfonate solution, and preferably a color value not exceeding 8R, which remains substantially unchanged upon heating said solution at a temperature substantially from i 245 to 255 F. for in excess of hours and preferably in excess of 168 hours. For convenience the above mentioned group members will be hereinafter collectively referred to as heat stabilizing agent.

Any organic solvent may be used in the .practice of the invention provided the sulfonate to be treated is substantially soluble therein. The solvents may be either Of the water miscible or water immiscible type. Suitable solvents among the former are, for instance, aliphatic alcohols and particularly ethyl-, propyl-, and butyl alcohol. Preferred solvents, however, are those that will not appreciably dissolve inorganic salts and are substantially of the water immiscible type. Such solvents of this kind are for instance petroleum oil distillates or any fraction thereof, benzol and its homologs, naphtha, carbon tetrachloride, tetrachlorethane, chloroform, etc. and, in general, any aromatic or aliphatic or aryl or aralkyl hydrocarbon or hydrocarbon mixture, including their halogenated derivatives of the aforedescribed character and nature. The solvents to be used in accordance with the invention should be substantially neutral to the action of the heat stabilizing reagent. where the solvent is to be removed [after the viscosity reducing treatment, it is desirable to have the boiling range of such solvent sufficiently low to permit removal in the customary manner, such I as by distillation in vacuo or Otherwise, withoutcausing thereby any decomposition of th mahogany sulfonates. In such cases it is of advantage that the boiling point be so low and prefera'bly between '15 and 250 F. as to enable the removal of the solvent at ordinary temperatures without the necessity of resorting to vacuum :dis-

,tillation.

. The petroleum mahogany sulfonate which is subjected to the heat stabilization reaction is nore mally one derived from the acid refining, with fuming sulfuric acid, of a petroleum oil distillate stock under sulfonating conditions of acid amount .and temperature in accordance with conven- .tional refining practice. In such conventional fuming sulfuric acid refining an oil layer and acid sludge layer are formed, the former containing dissolved therein petroleum mahogany sulfonic acids collectively referred to as mahogany petroleum sulfonic acids. These are recovered from the oil layer in accordance with conventional methods in the form of solutions of these sulfonic acids or their salts (the latter being collectively termed petroleum mahogany sulfonates) in a portion of the oil relatively tenaciously occluded by these sulfonic bodies. This occluded oil is generally referred to in the art as retained oil. The petroleum sulfonic acids or sulfonate oil compositions normally contain about to of retained oil and to of the petroleum mahogany sulfonic material, and up to about 5% of Water.

The heat stabilization agent in accordance with the invention may be any substantially water soluble inorganic or organic derivative of hyposulfurous acid (H2S2O4) or of sulfoxylic acid (H2802) such as hyposulfites,sulfoxylates, oxymethan sulfonates and oxymethan sulfines, the two last mentioned substances being respectively derivatives of oxymethan sulfonic acid and of oxymethan sulfinic acid; oxymethan sulfonates and oxymethan sulfines are obtained by the interaction of formaldehyde and hyposulfites and sulfoxylates respectively. Preferred heat stabilizing agents in accordance with the invention are substantially water soluble metal hyposulfites (often referred to in commerce as hydrosulfites), particularly alkali metal hyposulfites and substantially water soluble metal formaldehyde sulfoxylates and preferably alkali metal formaldehyde sulfoxylates. Within the preferred scope of the invention at least 0.25% and preferably 0.5 to 2.5 of the heat stabilizing agent by weight of sulfonate in solution is used. Though amounts in excess of 2.5% heat stabilizing agent may be employed, it has been found in normal practice that such excess is usually not required to obtain the desired heat stability under the rigid conditions of heat stability test herein specified.

Within the preferred embodiment of the invention a simultaneous color improving of the petroleum mahogany sulfonate solution by at least 1R In many cases, particularly will be obtained by the treatment provided the solution treated is capable of color improving.

Amounts appreciably in excess of 2.5% heat stabilizing agent, however, do not normally result in 5 any further color improving or improving in heat stability of the sulfonates over that already obtained with about 2.5% of the agent.

The amounts of water necessary for the practice of the invention are determined primarily upon the amount of stabilizing agent used in the treatment. The water should be present in amounts sufficient to dissolve at least a relatively large portion of the stabilizing agent as the same effectively acts primarily in aqueous solution. 15 Even though the total quantity of heat stabilizing agent is not all at once in aqueous solution, the agent as it reacts in solution is usually taken out of its aqueous phase and new heat stabilizing agent will go into solution provided the heat stabilizing agent possesses a greater water solubility than the product or salt resulting from this reaction. Generally at least 0.5 and preferably at least 3% of water should be present during the treatment. In most cases it is preferred, however, and particularlywhere use is made of the dehydration step as hereinafter described in greater detail, to have considerably more Water present. Thus, for instance, the stock conventionally going to the dehydrator contains water equivalent to approximately to by weight of sulfonate present and may be used as such with this water content.

The temperature of reaction is not critical. Somewhat elevated temperatures may be at times desired, particularly when-reacting the product in the presence of relatively small amounts of water in order to initiate or maintain the reaction. When operating within the preferred range and embodiment of the invention, however, i. e., when utilizing the process as part of the dehydration step as hereinafter described, the temperature of dehydration will aid in the effectiveness of the stabilizing reaction. This temperature of dehydration is usually between approximately 220 and 250 F.

The heat stabilizing agent may be added to a petroleum mahogany sulfonate stock as it may be for instance obtained after having been previously subjected to a given color improving procedure and possessing as a result thereof a given color value. Thus it may be added to and the reaction in accordance with the invention may be carried out with a product obtained for instance after applying a hypochlorite treatment in accordance with the Blumer Patent No. 2,201,119 or a product obtained with a chlorite treatment in accordance with the Liberthson and Blumer Patent No. 2,307,743 above referred to, whereby the so pre-treated stock may have any 60 desired color value covering the entire range from partial to maximum color improving obtainable for that stock. Alternatively the process is applicable to raw untreated stock.

Unless the color value of the petroleum ma- 66 hogany solution is already at the best possible minimum for that solution, a color improving over that of the starting material will result from the use of the novel process. The improvement in color value, however, may vary depend- 70 ing inter alia upon the nature, origin or prior treatment of the solution or the stock from which it is obtained, as well as upon the amount of heat stabilizing agent used. In any event, however, the resulting products will emerge substan- 7'5 tially heat stable. Thus in those cases in which cosity of the solution is sufficiently low at the desired or selected temperature of treatment to permit the intimate contact between the reactants. In most cases, however, a ratio of mahogany sulfonate to solvent of substantially 2 to 1 (by weight) will give satisfactory results. Sulfonate concentrations above 70 to 75% sulfonate content are normally not desirable for direct reaction without suitable extension. As a mode of agitation, any conventional method such as stirring, steam blowing, shaking, etc. may be used.

Though in the operation of the procedure in accordance with the invention any of the aforementioned solvents may be used with advantage, I prefer to use as the solvent that hydrocarbon fraction, the acid refining of which furnished the crude mahogany sulfonate stock and which is carried as retained oil. The crude mahogany sulfonate-retained oil stock constitutes as such a convenient mahogany sulfonate solution that may be subjected directly to treatment in accordance with the invention. 1

The heat stabilizing agent in accordance with the invention may be added as such, or within the preferred procedure, by way of a substantially aqueous solution. The reaction in which the heat stabilizing agent is involved is productive of salts which may impair even in relatively small quantities, the emulsifying and other characteristics of the sulfonates and the resultant products should be preferably subjected therefore to a salt removal step. For this reason it is of advantage and preferred to apply the procedure in accordance with the invention as a step in the refining of ap'etroleum mahogany sul fonate, utilizing it at the point of dehydration of the mahogany soap as it comes from theneutralizing step of the acidified oil and after re-' moval by distillation of the alcohol used for sulfonate extraction from the neutralization batch. When proceeding in this manner requisite amounts of the heat stabilizing agent are added to the aqueous soap solution and dehydration is carried on in the usual manner, 1. e., at a temperature between 220-250 F., thus obtaining simultaneously with dehydration a color improvei ment which when carried to, its maximum extent using the appropriate amounts of stabiliz ing agent, will yield eventually a product after removal of inorganic salts having a maximum obtainable reduction in Lovibond color value and being substantially heat stable (within the rigid conditions of test herein specified). In this way no special color improvement procedure is necessary, no supplemental means or equipment are required to treat the product and the conventional steps are carried on without any material change except solely for the simple addition. of

stabilization agent in the dehydration step.

Within the preferred application of the invention, the treatment with the stabilizing agent is 77' carried out at a neutral to alkaline pH. The stabilizing agent can be added to a petroleum mahogany solution while the same is at an acid pH. This permits addition of the stabilization agent to the acidified oil prior to neutralization Sodium sulfonate and 70% oil.

' 60 sodium'sulfonate,

and alcohol extractionofthe sulfonates. In such case when dehydrating the extracted neutralized sulfonate stock, after prior removal'of alcohol, the stabilization agent, having been carriedinto the extract, acts to obtain the desired heat stability and color reduction. 4 The following examples are furnished byway of illustrationand not of limitation:

Example I 100 lbs. of petroleum mahogany sulfonate stock produced by the. conventional anhydrous SO: treatmentof a Mid-continent mineral oil of 500 seconds Saybolt at 100 F. containing about 60% sodium mahogany sulfonates and about 40% retained oil and having an initial color value of 7.5R were mixed with 100 lbs. of water containing dissolved therein about lb. of sodium hyposulfite (sodium'hydrosulfite of commerce). The mixture was agitated by steam blowing and heated to 250 F. untilcompletely dehydrated. The Lovibond color of the dehydrated material was 4R,-equivalent to a color reduction of 46.5% compared'with the original.

Example II 100 lbs. of a petroleum mahogany sulfonate stool; produced by the furic acid refining of the same mineral oil speci-. fled inExample I, having a sulfonate content of about and a retained oil content of about 40% and possessing a Lovibond color value cell 10% white oil solution) of 4.3R was carried through the procedure described in Example I, using however in this case 2% lbs. of sodium formaldehyde sulfoxylate. The mix was agitated and heatedpto 250 F. until completely dehydrated. The final color value of the dehydrated material was 1.8R, i. e., a color decrease of about 53% comparedwith the original.

Example III 100 lbs. of thesame mineral oil specified in Examples I and II was subjected to conventional fuming sulfuric acid treatment, the acid treated oil after removal of acid sludge was extended with an equal volume of benzol and then neutralized. The benzol was removed by distillation. The sulfonate stock at this point consisted of about 30% The Lovibond color of the stock was 5.3R. 1 lb. of sodium formaldehyde sulfoxylate in the form' of a 10% aqueous solution was added. After agitation and de-- hydration at a temperature of about 250 F., the stock had a color value of 30R, i. e., a color decrease of 42.5% compared with-the original.

Example IV stock obtained from the same oil and in the manner: specified-in Example II, having an original Lovibond color value of 9.8R and containing about retained oil and 5 water was heated at 250 F. with 1 lb. sodium formaldehyde sulfoxylate for one-half hour. The resultant'stock was thereafter subjected to a salt removal step by means of extending with an equal volume of ethyl alcohol, permitting thesalts to settle out, withdrawing the alcohol layer and stripping the same of alcohol by distillation. The Lovibond color value of the finished purified m'aterial'w'as 3.8RL. i. e., a color decrease of 61% compared with the original. I

conventional fuming sul-.

Example V 100 lbs. of the petroleum mahogany. sulfonate stock described in Example 1, containing 60% of sodium sulfonate and 40% retained oil and having a Lovibond color value of SE was intimately contacted with lbs. of a 10% solution of sodium hypochlorite at a temperature of 220 F. for one hour. The resultant color produced by this treatment was 3.8R. To the so decolorized sulfonate stock was added /2 lb. sodium formaldehyde sulfoxylate. The batch was agitated for one-half hour while heating to between 220 and 250 F. for dehydration. The final color was 1.8R, Le, a color decrease of 51% as compared with the hypochlorite treated stock.

Example VI 100 gallons of an acidified oil obtained by the conventional fuming sulfuric acid treatment of the same oil as specified in Example I was extracted with gallons of 50% aqueous alcohol. 1 1b. of drysodium formaldehyde sulfoxylate was stirred into this alcoholic extract of mahogany sulfonic acids. The entire batch was then neutralized with caustic soda (27 B.) to phenolphthalein end point. The alcohol was then distilled off and the alcohol-free solution heated to 220-250 F. for dehydration. The final color obtained was R. as compared with an original of 5.03., the latter having been determined from a sample finished for color determination prior to the addition of the stabilizing agent; this represents a color reduction of 50% as compared with the original.

The various products obtained in accordance with the foregoing examples were subjected to a heat stability test in the following manner:

' 100 grams of the respective products were heated in iron sealed containers at a temperature of 250 F. (thermostatically controlled). The samples were periodically inspected for color values and were found to remain substantially unchanged in their original Lovibond color values after heating up to 240 hours.

The sulfonate product obtained after hypo-- chlorite treatment as set forth in Example V, having a Lovibond color value of 3.8R (prior to the sulfoxylate treatment). was subjected to the same heating test in the sealed iron containers at 250 F. The sample was periodically inspected and showed a continuing deterioration of the color beginning to be appreciable after about 24 hours and reaching after a period of about 120 hours, an increase to a Lovibond color value of 75R, i. e., an increase to almost 200% of the original.

All color values referred to in the specification and claims are intended to designate color values obtained in accordance with the Lovibond system using /2 cells and 10% white oil solutions.

Where reference herein is made to a preferred color value of not exceeding 8B in connection with a petroleum mahogany sulfonate solution in accordance with the invention, it is intended to designate thereby such color value for a sulfonate content in said solution of at least 40%.

If within the preferred embodiment of the invention the same is practiced as a part of the conventional dehydration step of a petroleum mahogany sulfonate neutralization batch, it is for most purposes sufficient to dehydrate down to a water content of not exceeding about 5% by weight of sulfonate in solution.

The foregoing description is for purposes of illustration and not of limitation and it is therefore my intention that the invention be limited only by the appended claims or their equivalents wherein I have endeavored to claim broadly all inherent novelty.

I claim:

1. Process for heat stabilizing petroleum mahogany sulfonate solutions which comprises reacting, in-the. presence of water, a solution of petroleum mahogany sulfonate in an organic solvent for'said sulfonate, with at least one member selected from the group consisting of substantially water soluble inorganic and organic derivatives of hyposulfurous and sulfoxylic acid in amount and for a period of time sufiicient to substantially obtain a Lovibond color value for said solution remaining substantially unchanged upon heating said solution at from 245 to 255 F. for in excess of. substantially hours.

2. Process for heat stabilizing petroleum mahogany sulfonate solutions which comprises reacting a solution of petroleum mahogany sulfonate in an organic solvent for said sulfonate in the presence of at least 0.5 to 3% of water by weight of sulfonate insolution, with at least 0.25 to 2.5% by weight of sulfonate in solution of at least one member selected from the group consisting of substantially water soluble inorganic and organic derivatives of hyposulfurous and sulfoxylic acid for a period of time sufficient to substantially obtain a Lovibond color value for said solution remaining substantially unchanged upon heating said solution at irom 245 to 255 F. for from substantially 120 to 240 hours.

3. Process in accordance with claim 2 in which at least the major portion of said solvent is retained oil and in which said group member is alkali metal hyposulfite.

4. Process in accordance with claim 2 in which at least the major portion of-said solvent is retained oil and in which said group member is formaldehyde alkali metal hyposulfite.

5. Process in accordance with claim 2 in which at least the major portion of said solvent is retained oil and in which said group member is formaldehyde alkali metal sulfoxylate.

6. Process for heat stabilizing petroleum mahogany sulfonate solutions which comprises dehydrating a solution of petroleum mahogany sulfonate in an organic substantially water immiscible solvent for said sulfonate, while in intimate contact with an aqueous solution of at least 0.25 to 2.5% by weight of sulfonate in solution of at least one member selected from the group consisting of substantially water soluble inorganic and organic derivatives of hyposul furous and sulfoxylic acid and continuing the dehydration of said solution until a Lovibond color value for said solution is obtained remaining substantially unchanged upon heating said solution at from 245 to 255 F. for from substantially 120 to 240 hours.

7. Process in accordance with claim 6 in which at least the major portion of said solvent is retained oil and in which said group member is alkali metal hyposulfite. H

8. Process in accordance with claim 6 in which at least the major portion of said solvent is "retained oil and in which said group member is formaldehyde alkali metal hyposulfite.

9. Process in accordance with claim 6 in which at least the major portion of said solvent is retained oil and in which said group member is formaldehyde alkali metal sulfoxylate.

10. Process for heat stabilizing petroleum mahogany sulfonate solutions which comprises dehydrating a petroleum mahogany sulfonate neutralization batch obtained in the neutralization of an acidified oil, derived from the fuming sulfuric acid refinin of a petroleum oil distillate in the presence of at least 0.25 to 2.5% by weight of sulfonate in solution of at least one member selected from the group consisting of substantially water soluble inorganic and organic derivatives of hyposulfurous and sulfoxylic acid, continuing the dehydration of said batch until substantially all water in excess of substantially 5% by weight of sulfonate in solution has been re-i moved, and recovering a petroleum mahogany sulfonate retained oil solution having a Lovibond color value remaining substantially unchanged upon heating said solution at from 245 to 255 and being not in excess content of at least 40%.

11. Process in accordance with claim 10 in which said group member is alkali metal hyposulfite.

of SE for a sulfonate F. for from substantially 120 to 240 hours 10 12. Process in accordance with claim 10 in which said group member is formaldehyde alkali metal hyposulfite.

13. Process in accordance with claim 10 in which said group member is formaldehyde alkali metal sulfoxylate.

MANUEL BLUMER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

